Most of the existing IR spectral imaging systems require focal plane detector arrays (FPAs) that have to be highly sensitive and cooled in order to compensate, during the optical detection, for the reduction of the photon flux caused by spectrum-scanning operation. There remains a need, therefore, in a system enabling an optical data acquisition mode that does not require the cooling of the used detector(s), which detectors can be less sensitive to photons in the IR but yet well fit for continuous monitoring applications. There also remains a need in an IR imaging system the operation of which is substantially not susceptible to motion artifacts (which is a common problem with spectrally-scanning systems causing errors in either the spectral data, spatial data, or both).